Collagen-based cell migration models in vitro and in vivo.

Different in vitro collagen-based cell invasion models are evaluated, employing either pepsinized or non-pepsinized collagen extracts, and their structure to connective tissue in vivo is compared, and it is shown that, depending on the collagen source, in vitro models yield homogeneous fibrillar texture with a quite narrow range of pore size variation, whereas all in vivo scaffolds comprise a range from low- to high-density fibrilar networks and heterogeneous p